Apparatus for mounting a sensor having a hermetic seal

ABSTRACT

Apparatus and Methods for fabricating apparatus having a hermetic seal to seal a portion of an apparatus, for example and without limitation, a portion having a MEMS sensor. One such method uses crimping devices to compress a seal in a cavity formed in a housing that includes a MEMS sensor attached to a stress isolator. Under such compression, the seal deforms to hermetically seal surfaces around the inside, outside and bottom of the stress isolator.

RELATED APPLICATIONS

This application is a continuation of co-pending application Ser. No.14/170,355 filed Jan. 31, 2014, and claims the benefit thereof.

TECHNICAL FIELD

One or more embodiments relate to apparatus having a hermetic orairtight seal, and one or more further embodiments relate to methods offabricating such apparatus.

BACKGROUND

Many conventional methods exist for forming seals which prevent leakageof liquid, gas, and the like from one section of a package to another.For example, conventional methods for forming seals entail: (a) usingO-rings; (b) welding; (c) soldering; and (d) gluing. Many suchconventional methods are acceptable in environments where sealing is notvery sensitive or important. However, in many environments, includingthose where sensors are placed along different sections of a package tomeasure pressure, obtaining an airtight or hermetic seal is importantand conventional methods are not adequate.

In typical conventional pressure sensor devices, a convoluted, thin,metal diaphragm is welded in a pressure path to seal (so as to reduceleakage of gas from) a gas-filled chamber. In manufacturing other typesof conventional pressure sensor devices, a metal housing is fabricatedusing stainless steel alloys (due to their anti-corrosioncharacteristics). In such cases, a sealing method typically entails theuse of a laser beam or an electron beam (“e-beam”) to melt the metal toform a hermetic seal.

A MEMS (“Micro-Electro-Mechanical Systems”) pressure sensor device usesa silicon base which is mounted on a metal, for example, Kovar or Invar,whose coefficient of thermal expansion closely matches that of thesilicon base (in general, stainless steel alloys cannot be used). Due tocontinuing requirements for low cost pressure sensor devices, it isdesirable that a metallic housing for such devices be made frommaterials such as brass, copper and aluminum, and not stainless steel.However, joining thermally matched metal (for example, Kovar or Invar)to a metallic housing (made, for example, of thermally mismatched metalssuch as brass, copper or aluminum) using a conventional laser weldingmethod typically results in weld cracks. In other words, conventionallaser welding methods used with these metals have been unsuccessful informing hermetic seals. Further, alternate sealing methods such asbrazing and soldering require processes at temperatures above 800° C.,which high temperatures are unacceptable for use in fabricating MEMSsensor devices.

SUMMARY

One or more embodiments relate to apparatus having a hermetic seal suchas, for example and without limitation, pressure sensor devices thatinclude MEMS sensors. One or more further embodiments relate to methodsfor fabricating such apparatus such as, for example and withoutlimitation, methods for fabricating pressure sensor devices that includeMEMS sensors without damaging such sensors. In particular, one or morefurther embodiments of methods for fabricating entail the use differenttypes of metal seals to seal portions of an apparatus so that MEMSsensors can be used. In further particular, one or more such furtherembodiments of methods for fabricating entail the use of crimpingdevices to pressure seal metal seals within the apparatus. In stillfurther particular, one or more such further embodiments of methods forfabricating provide hermetic sealing by compression forces at a leakrate equal to welding methods, and which do not cause leakage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of an apparatus having a hermetic sealthat is fabricated in accordance with one or more embodiments;

FIG. 1B shows cross sectional views of three apparatus embodiments ofthe apparatus shown in FIG. 1A a first apparatus embodiment that isfabricated in accordance with a first process embodiment that uses aradial seal, a second apparatus embodiment that is fabricated inaccordance with a second process embodiment that uses a “complete” seal,and a third apparatus embodiment that is fabricated in accordance with athird process embodiment that uses a “face” seal;

FIG. 2 is a perspective, exploded view of parts used to fabricate one ofmore first apparatus embodiments having a hermetic seal in accordancewith a first process embodiment, i.e., using a radial seal;

FIG. 3A is a perspective view of a collar used to fabricate one or moreembodiments;

FIG. 3B is a cross sectional view of the collar shown in FIG. 3A;

FIG. 4A is a perspective view of a stress isolator with an attached MEMSsensor that is used to fabricate one or more embodiments;

FIG. 4B is a cross sectional view of the stress isolator with anattached MEMS sensor shown in FIG. 4A;

FIG. 5A is a perspective view of a radial seal that is used to fabricateone or more first apparatus embodiments having a hermetic seal inaccordance with the first process embodiment;

FIG. 5B is a cross sectional view of the radial seal shown in FIG. 5A;

FIG. 6A is a perspective view of a housing that used to fabricate one ormore first apparatus embodiments having a hermetic seal in accordancewith the first process embodiment;

FIG. 6B is a cross sectional view of the housing shown in FIG. 6A;

FIG. 7 is an illustration of steps of a radial seal crimping processthat are carried out in accordance with one or more first processembodiments to fabricate one or more first apparatus embodiments;

FIG. 8 is a perspective, exploded view of parts used to fabricate one ormore second apparatus embodiments having a hermetic seal in accordancewith a second process embodiment, i.e., using a “complete” seal;

FIG. 9A is a perspective view of a collar used to fabricate one or moreembodiments;

FIG. 9B is a cross sectional view of the collar shown in FIG. 9A;

FIG. 10A is a perspective view of a stress isolator with an attachedMEMS sensor that is used to fabricate one or more embodiments;

FIG. 10B is a cross sectional view of the stress isolator with anattached MEMS sensor shown in FIG. 10A;

FIG. 11A is a perspective view of a “complete” seal that is used tofabricate one or more second apparatus embodiments having a hermeticseal in accordance with the second embodiment;

FIG. 11B is a cross sectional view of the “complete” seal shown in FIG.11A;

FIG. 12A is a perspective view of a housing that is used to fabricateone or more second apparatus embodiments having a hermetic seal inaccordance with the second embodiment;

FIG. 12B is a cross sectional view of the housing shown in FIG. 12A;

FIG. 13 is an illustration of steps of a “complete” seal crimpingprocess that are carried out in accordance with one or more secondprocess embodiments to fabricate one or more second apparatusembodiments;

FIG. 14 is a perspective, exploded view of parts used to fabricate oneor more third apparatus embodiments having a hermetic seal in accordancewith a third process embodiment, i.e., using a “face” seal;

FIG. 15A is a perspective view of a collar used to fabricate one or moreembodiments;

FIG. 15B is a cross sectional view of the collar shown in FIG. 15A;

FIG. 16A is a perspective view of a stress isolator with an attachedMEMS sensor that is used to fabricate one or more embodiments;

FIG. 16B is a cross sectional view of the stress isolator with anattached MEMS sensor shown in FIG. 16A;

FIG. 17A is a perspective view of a “face” seal that is used tofabricate one or more first apparatus embodiments having a hermetic sealin accordance with the third process embodiment;

FIG. 17B is a cross sectional view of the “face” seal shown in FIG. 17A;

FIG. 18A is a perspective view of a housing that is used to fabricateone or more second apparatus embodiments having a hermetic seal inaccordance with the second and the third process embodiments;

FIG. 18B is a cross sectional view of the housing shown in FIG. 18A; and

FIG. 19 is an illustration of steps of a “face” seal crimping processthat are carried out in accordance with one or more third embodiments tofabricate one or more third apparatus embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments will be described with reference to the figures, whereinlike components, parts, and so forth are designated by like referencenumerals throughout the various figures. Further, specific parameterssuch as pressure values, materials, size, dimensions, shapes, and thelike are provided herein, and are intended to be explanatory rather thanlimiting.

One or more process embodiments are directed to methods for forming ahermetic seal to seal a portion of an apparatus (such as, for exampleand without limitation, a pressure sensor apparatus or device), and inparticular, a portion such as, for example and without limitation, aportion having a MEMS (“Micro-Electro-Mechanical Systems”) sensor. Inaccordance with one or more such process embodiments, the methods entailforming a hermetic seal by deforming a seal in a cavity formed in ahousing that includes a MEMS sensor attached to a stress isolator. Inaccordance with one or more such process embodiments, the seal can bemade of metal, which metal is preferably a soft metal such as, forexample and without limitation, copper or copper alloy. However, one ormore further process embodiments include the use of other metals ornon-metals capable of forming a hermetic seal. It is believed that oneor more of the process embodiments act provide an airtight or hermeticseal by using mechanical pressure to “melt” or “soft anneal” a metalseal (i.e., to form a “solder-like” seal which is airtight or hermetic).

In addition, one or more apparatus embodiments are directed to apparatushaving a hermetic seal that seals a portion of the apparatus, and inparticular, a portion such as, for example and without limitation, aportion having a MEMS sensor.

FIG. 1A is a perspective view of apparatus 1 which has a hermetic sealand which is fabricated in accordance with one or more processembodiments. As shown in FIG. 1A, apparatus 1 includes: housing 2 havingcavity 4 therein, stress isolator 8 with attached MEMS sensor 12, andcollar 10. MEMS sensor 12 is typically used to sense and measure thepressure of a fluid or liquid. Not shown in FIG. 1A is a hermetic sealdisposed between stress isolator 8 and an inner wall of cavity 4.

FIG. 1B shows cross sectional views of three apparatus embodiments ofapparatus 1 shown in FIG. 1A. The first apparatus embodiment shown inFIG. 1B is fabricated in accordance with a first process embodiment thatuses a radial seal, and is described below with reference to FIGS. 2-7;the second apparatus embodiment shown in FIG. 1B is fabricated inaccordance with a second process embodiment that uses a “complete” seal,and is described below with reference to FIGS. 8-13; and the thirdapparatus embodiment shown in FIG. 1B is fabricated in accordance with athird process embodiment that uses a “face” seal, and is described belowwith reference to FIGS. 14-19.

FIG. 2 is a perspective, exploded view of parts used to fabricate one ormore first embodiments of a pressure sensor apparatus having a hermeticseal in accordance with the first process embodiment, i.e., using aradial seal. As shown in FIG. 2, cavity 4 is formed in housing 2 (forexample and without limitation, a metal housing) of the apparatus. Inaccordance with this first apparatus embodiment, and as further shown inFIG. 2, the first apparatus embodiment is fabricated using radial seal 6(formed, for example and without limitation, of a soft metal such ascopper), stress isolator 8, and collar 10 (formed, for example andwithout limitation, of high strength steel). As further shown in FIG. 2,MEMS sensor 12 is attached to stress isolator 8.

FIG. 3A is a perspective view of collar 10, and FIG. 3B is a crosssectional view of collar 10; FIG. 4A is a perspective view of stressisolator 8 with attached MEMS sensor 12, and FIG. 4B is a crosssectional view of stress isolator 8 with attached MEMS sensor 12; FIG.5A is a perspective view of radial seal 6, and FIG. 5B is a crosssectional view of radial seal 6; and FIG. 6A is a perspective view ofhousing 2 having cavity 4 disposed therewithin, and FIG. 6B is a crosssectional view of housing 2 having cavity 4 disposed therewithin.

In accordance with one or more such first apparatus embodiments, housing2 can be made of a metal, such as, for example and without limitation,stainless steel, brass, and aluminum or it may be fabricated as aplastic molded part having a metal insert. In addition, housing 2 can bemade of other materials or metal composites so long as they are capableof withstanding the stress and strain of the fabrication processdescribed herein, and they have material characteristics suitable tomaintaining the hermetic seal. In further addition, housing 2 includescavity 4. In accordance with one or more such embodiments, the walls ofcavity 4 may have any shape that is suitable to accept radial seal 6snugly therein (as used herein, the term snugly refers to a tight fit,but not so tight as requiring a press fit). Note that for thisembodiment, an aperture in housing 2 that extends to the bottom ofcavity 4 (refer to FIG. 6B) does not extend up into, and between thewalls of, cavity 4.

In accordance with one or more embodiments, stress isolator 8 is made ofa metal having a low coefficient of thermal expansion, and stressisolator has a diameter that is smaller than the diameter of cavity 4.In accordance with one or more such embodiments, a suitable metal havinga suitably low coefficient of thermal expansion can be, for example andwithout limitation, an iron base alloy such as, for example and withoutlimitation, Invar or a Kovar alloy containing, by weight, 42% nickel andthe balance iron.

In accordance with one or more embodiments, collar 10 can be made fromhigh strength stainless steel such as, for example and withoutlimitation, alloys and machine-able stainless steels like SUS300 series,SUS400 series, and SUS600 series stainless steels. In accordance withone or more embodiments, collar 10 has walls that fit snugly around theouter walls of cavity 4.

In accordance with one or more such first apparatus embodiments, radialseal 6 (illustrated in FIGS. 5A and 5B) can be made from a metal suchas, for example and without limitation, soft copper—where the term softcopper generally means about 100% copper and little or no other alloy.In addition, radial seal 6 can be made from other materials such as, forexample and without limitation, Teflon, aluminum, and any other softmetal materials such as soft copper alloys. When the apparatus isassembled in accordance with one or more first process embodiments,radial seal 6 surrounds, or encapsulates stress isolator 8, in a radialmanner. In accordance with one or more embodiments, the diameter ofradial seal 6 is smaller than the diameter of cavity 4, but is largerthan the diameter of stress isolator 8 to create a snug fit between thetwo. In accordance with one or more embodiments, although radial seal 6is shown as having a cylindrical shape, radial seal 6 is not limited tothis shape. In accordance with one or more embodiments, the walls ofradial seal 6 do not extend to the top of the walls of cavity 4.

Although FIG. 4A shows MEMS sensor 12 attached to the top of stressisolator 8, further embodiments exist where MEMS sensor is placed atlocations on stress isolator 8 other that at the top thereof. Inaccordance with one or more embodiments, MEMS sensor 12 can be anyconventional MEMS sensor currently available. In addition, in accordancewith one or more embodiments, stress isolator 8 can be shaped in anymanner so long as it can be surrounded by radial seal 6.

FIG. 7 is an illustration of steps (of a radial seal crimping process)that are carried out in accordance with one or more first processembodiments to fabricate one or more first apparatus embodiments. First,first crimper 20 is used to place radial seal 6 within cavity 4 ofhousing 2. Next, first crimper 20 is used to place stress isolator 8with attached MEMS sensor 12 within radial seal 6 in cavity 4. Next,first crimper 20 is used to exert pressure on top of stress isolator 8(for example and without limitation, a pressure of about 0.5 ton psi) topress stress isolator 8 and attached MEMS sensor 12 down completelyinside radial seal 6. Next, second crimper 30 is used to place collar 10above stress isolator 8 so that its walls extend around the outer wallof cavity 4. Next, second crimper 30 is used to exert pressure on top ofcollar 10 (for example and without limitation, a pressure of about 2tons psi) so that the walls of cavity 4 are crimped down (also referredto as compressed down) on radial seal 6 and stress isolator 8. Inresponse, radial seal 6 is deformed and it fills gaps (it is believed tohave “melted”) between the outside of stress isolator 8 and the innerwalls of cavity 4, and the walls of cavity 4 are crimped down on stressisolator 8 to provide a retaining force therefor within housing 2—thisretaining force prevents stress isolator 8 from being evicted fromcavity 4 under applied pressure of gas or liquid. As a result, radialseal 6 has been deformed to provide a hermetic and airtight seal incavity 4 of housing 2 between the outer wall of stress isolator 8,radial seal 6, and the inner wall of cavity 4. In other words, a metalseal is compressed in a cavity bounded by cavity walls that is formed ina housing, which housing also includes a sensor attached to a stressisolator (also referred to as an stress isolator pedestal), i.e., anexternal crimper is press fitted outside the cavity walls, and as aresult, the cavity walls are bent down on the stress isolator pedestaland, a retaining force is exerted on the stress isolator pedestal.

FIG. 8 is a perspective, exploded view of parts used to fabricate one ormore second embodiments of a pressure sensor apparatus having a hermeticseal in accordance with the second process embodiment, i.e., using a“complete” seal. As shown in FIG. 8, the apparatus that is fabricated inaccordance with the second process embodiment is similar to theapparatus described above that is fabricated in accordance with thefirst process embodiment, except that the housings and the seals aredifferent from each other. In addition, as will be described furtherbelow, the crimping processes used to fabricate the respective hermeticseals are different.

As shown in FIG. 8, cavity 24 is formed in housing 22 (for example andwithout limitation, a metal housing) of the apparatus. In accordancewith this second apparatus embodiment, and as further shown in FIG. 8,the second apparatus embodiment is fabricated using “complete” seal 26(formed, for example and without limitation, of a soft metal such ascopper), stress isolator 8, and collar 10 (formed, for example andwithout limitation, of high strength steel). As further shown in FIG. 8,MEMS sensor 12 is attached to stress isolator 8 as was described abovewith respect to the first apparatus embodiment.

FIG. 9A is a perspective view of collar 10, and FIG. 9B is a crosssectional view of collar 10; FIG. 10A is a perspective view of stressisolator 8 with attached MEMS sensor 12, and FIG. 10B is a crosssectional view of stress isolator 8 with attached MEMS sensor 12; FIG.11A is a perspective view of “complete” seal 26, and FIG. 11B is a crosssectional view of “complete” seal 26; and FIG. 12A is a perspective viewof housing 22 having cavity 24 disposed therewithin, and FIG. 12B is across sectional view of housing 22 having cavity 24 disposedtherewithin.

The materials of which collar 10 and stress isolator 8 with attachedMEMS sensor 12 are fabricated have been described above.

In accordance with one or more such second apparatus embodiments,housing 22 can be made of metal, such as, for example and withoutlimitation, stainless steel, brass, and aluminum or it may be fabricatedas a plastic molded part having a metal insert. In addition, housing 22can be made of other materials or metal composites so long as they arecapable of withstanding the stress and strain of the fabrication processdescribed herein, and they have material characteristics suitable tomaintaining the hermetic seal. In further addition, housing 22 includescavity 24. In accordance with one or more such embodiments, cavity 24may have any shape that is suitable to accept “complete” seal 26 snuglytherein. Note that for this embodiment, duct (or pipe) in housing 22that extends into cavity 24 (refer to FIG. 12B).

In accordance with one or more such second apparatus embodiments,“complete” seal 26 (illustrated in FIGS. 11A and 11B) can be made from ametal such as, for example and without limitation, soft copper. Inaddition, “complete” seal 26 can be made from other materials such as,for example and without limitation, Teflon, aluminum, and other softmetal materials such as soft copper alloys. During apparatus assembly inaccordance with one or more second process embodiments, stress isolator8 sits snugly in, and on top of, “complete” seal 26 once they are placedwithin cavity 24 of housing 22. In accordance with one or moreembodiments, “complete” seal 26 is shown as having a toroidal shape withan open top. However, “complete” seal 26 is not limited to thisparticular shape, and further embodiments exist where “complete” seal 26may have any suitable shape so long as stress isolator 8 can fit in“complete” seal 26. In accordance with one or more embodiments, thewalls of “complete” seal 26 do not extend to the top of the walls ofcavity 24.

FIG. 13 is an illustration of steps (of a “complete” seal crimpingprocess) that are carried out in accordance with one or more secondprocess embodiments to fabricate one or more second apparatusembodiments. First, third crimper 25 is used to place “complete” seal 26within cavity 24 of housing 22. Next, first crimper 20 is used to placestress isolator 8 with attached MEMS sensor 12 in “complete” seal 26 incavity 24. Next, first crimper 20 is used to exert pressure on top ofstress isolator 8 (for example and without limitation, a pressure ofabout 0.5 ton psi) to press stress isolator 8 and attached MEMS sensor12 completely in between the walls or edges of “complete” seal 26. Next,second crimper 30 is used to place collar 10 above stress isolator 8 sothat its walls extend around the outer wall of cavity 24. Next, secondcrimper 30 is used to exert pressure on top of collar 10 (for exampleand without limitation, a pressure of about 2 tons psi) so that thewalls of cavity 24 are crimped down on “complete” seal 26 and stressisolator 8. In response, “complete” seal 26 is deformed and it fillsgaps (it is believed to have “melted”) between the outside of stressisolator 8 and the inner walls of cavity 24, and the walls of cavity 24are crimped down on stress isolator 8 to provide a retaining forcetherefor within housing 22. As a result, “complete” seal 26 has beendeformed to provide a hermetic and airtight seal in cavity 24 of housing22 between the outer wall of stress isolator 8, “complete” seal 26, andthe inner wall of cavity 24.

FIG. 14 is a perspective, exploded view of parts used to fabricate oneor more third embodiments of a pressure sensor apparatus having ahermetic seal in accordance with the third process embodiment, i.e.,using a “face” seal. As shown in FIG. 14, the apparatus that isfabricated in accordance with the third process embodiment is similar tothe apparatus described above that is fabricated in accordance with thesecond process embodiment, except that the seals are different from eachother. In addition, as will be described further below, the crimpingprocesses used to fabricate the respective hermetic seals are different.

As shown in FIG. 14, cavity 24 is formed in housing 22. In accordancewith this third apparatus embodiment, and as further shown in FIG. 14,the third apparatus embodiment is fabricated using “face” seal 36(formed, for example and without limitation, of a soft metal such ascopper), stress isolator 8, and collar 10 (formed, for example andwithout limitation, of high strength steel). As further shown in FIG.14, MEMS sensor 12 is attached to stress isolator 8 as was describedabove with respect to the first apparatus embodiment.

FIG. 15A is a perspective view of collar 10, and FIG. 15B is a crosssectional view of collar 10; FIG. 16A is a perspective view of stressisolator 8 with attached MEMS sensor 12, and FIG. 16B is a crosssectional view of stress isolator 8 with attached MEMS sensor 12; FIG.17A is a perspective view of “face” seal 26, and FIG. 17B is a crosssectional view of “face” seal 36; and FIG. 18A is a perspective view ofhousing 22 having cavity 24 disposed therewithin, and FIG. 18B is across sectional view of housing 22 having cavity 24 disposedtherewithin.

The materials of which collar 10 and stress isolator 8 with attachedMEMS sensor 12 are fabricated have been described above. In addition,the materials of which housing 22 is fabricated have been describedabove. In accordance with one or more embodiments, cavity 24 may haveany shape that is suitable to accept “face” seal snugly therein.

In accordance with one or more such third apparatus embodiments, “face”seal 36 (illustrated in FIGS. 17A and 17B) can be made from a metal suchas, for example and without limitation, soft copper. In addition, “face”seal 36 can be made from other materials such as, for example andwithout limitation, Teflon, aluminum and any other soft metal materials.During apparatus assembly in accordance with one or more third processembodiments, stress isolator 8 sits snugly in cavity 24 on top of “face”seal 36 once they are placed in the cavity 24 of the housing 22. Inaccordance with one or more embodiments, “face” seal 36 is shown to beshaped as a disk. However, “face” seal 36 is not limited to thisparticular shape, and further embodiments exist where “face” seal mayhave any suitable shape so long as “face” seal 36 can sit snugly withinthe walls of cavity 24.

FIG. 19 is an illustration of steps (of a “face” seal crimping process)that are carried out in accordance with one or more third processembodiments to fabricate one or more third apparatus embodiments. First,first crimper 20 is used to place “face” seal 36 within cavity 24 of thehousing 22. Next, first crimper 20 is used to place stress isolator 8with attached MEMS sensor 12 in cavity 24. Next, first crimper 20 isused to exert pressure on top of stress isolator 8 (for example andwithout limitation, a pressure of about 0.5 ton psi) to press stressisolator 8 and attached MEMS 12 down completely on “face” seal 36. Next,second crimper 30 is used to place collar 10 above stress isolator 8 sothat its walls extend around the outer wall of cavity 24. Next, secondcrimper 30 is used to exert pressure on collar 10 (for example andwithout limitation, a pressure of about 2 tons psi) so that the walls ofcavity 24 are crimped down on “face” seal 36 and stress isolator 8. Inresponse, “face” seal is deformed and it fills gaps (it is believed tohave “melted”) between a bottom surface of stress isolator 8 andsurfaces of the inner walls of cavity 24, and the walls of cavity 24 arecrimped down on stress isolator 8 to provide a retaining force thereforwithin housing 22. As a result, “face” seal 36 has been deformed toprovide a hermetic and airtight seal in cavity 24 of housing 22 betweenthe bottom surface of stress isolator 8, “face” seal 36, and the innerwall of cavity 24.

Embodiments described above are exemplary. For example, numerousspecific details are set forth such as parts, dimensions, temperatureranges, materials, mechanical design, etc. to provide a thoroughunderstanding of the present invention. However, as one having ordinaryskill in the art would recognize, the present invention can be practicedwithout resorting to the details specifically set forth. As such, manychanges and modifications may be made to the description set forth aboveby those of ordinary skill in the art (i.e., various refinements andsubstitutions of the various embodiments are possible based on theprinciples and teachings herein) while remaining within the scope of theinvention. In addition, materials, methods, and mechanisms suitable forfabricating embodiments have been described above by providing specific,non-limiting examples and/or by relying on the knowledge of one ofordinary skill in the art. Materials, methods, and mechanisms suitablefor fabricating various embodiments or portions of various embodimentsdescribed above have not been repeated, for sake of brevity, wherever itshould be well understood by those of ordinary skill in the art that thevarious embodiments or portions of the various embodiments could befabricated utilizing the same or similar previously described materials,methods or mechanisms. As such, the scope of the invention should bedetermined with reference to the appended claims along with their fullscope of equivalents.

What is claimed is:
 1. An apparatus comprising: a housing with a top anda bottom and a hole that passes through the housing from the top to thebottom wherein the housing further comprises a first cavity with a firstinner wall, a first outer wall and a first cavity bottom and wherein thehousing further comprises a second cavity with a second inner wall, asecond outer wall and a second cavity bottom and both the first cavityand second cavity extend down into the housing from the top and surroundthe hole wherein the first outer wall of the first cavity is the secondinner wall of the second cavity; a seal with a toroidal shape and anopen top, wherein the seal is located in the first cavity bottom andsurrounds the first inner wall; an isolation member coupled to a sensorand extending down into the first cavity such that the isolation memberextends down into the open top of seal; and a collar coupled to thehousing and extending down into the second cavity.
 2. The apparatus ofclaim 1, wherein the seal is deformed such that it seals the isolationmember to the housing.
 3. The apparatus of claim 2 wherein the sensor isa pressure sensor.
 4. The apparatus of claim 1, wherein the housing iscylinder shaped.
 5. The apparatus of claim 1, wherein the seal is madefrom copper.
 6. The apparatus of claim 1, wherein the seal is a copperalloy.
 7. The apparatus of claim 1, wherein the sensor is a MEMS sensor.8. The apparatus of claim 1, wherein the collar is made from steel. 9.The apparatus of claim 1, wherein the housing comprises of one or moreof stainless steel, brass and aluminum.
 10. The apparatus of claim 1wherein the collar has a first hole that passes through the collarwherein, the first hole is coaxial with the hole in the housing, firstcavity and second cavity.
 11. An apparatus having a hermetic sealcomprising: a housing with a top and bottom and a hole that passesthrough the housing from the top to the bottom wherein the housingfurther comprises a first cavity that extends down into the housing fromthe top and surrounds the hole and has a cavity bottom and wherein thehousing further comprises a protrusion that surrounds the hole andextends up from the cavity bottom into the first cavity and wherein thehousing further comprises a second cavity that extends down into thehousing from the top and surrounds, and is coaxial with, the firstcavity; a seal with a toroidal shape with an open top located in thebottom of the first cavity wherein the seal surrounds the protrusion; anisolation member coupled to a sensor and extending down into the sealthrough the open top; and a collar that surrounds the isolation memberand is pressed down into the housing and into the second cavity.
 12. Theapparatus of claim 11, wherein the toroidal seal covers the bottom ofthe first cavity.
 13. The apparatus of claim 11, wherein the housing iscylinder shaped.
 14. The apparatus of claim 11, wherein the seal is madefrom copper.
 15. The apparatus of claim 11, wherein the seal is a copperalloy.
 16. The apparatus of claim 11, wherein the collar is made fromsteel.
 17. The apparatus of claim 11, wherein the housing comprises ofone or more of stainless steel, brass and aluminum.
 18. The apparatus ofclaim 11, wherein the collar has a first hole that passes through thecollar, and wherein the first hole is coaxial with the hole in thehousing, first cavity and second cavity.
 19. The apparatus of claim 11,wherein the sensor is a pressure sensor.
 20. An apparatus having ahermetic seal comprising: a housing with a top and bottom and a holethat passes through the housing from the top to the bottom wherein thehousing further comprises a first cavity that extends down into thehousing from the top and surrounds the hole and has a cavity bottom andwherein the housing further comprises a pipe that surrounds the hole andextends up from the cavity bottom into the first cavity and wherein thehousing further comprises a second cavity that extends down into thehousing from the top and surrounds, and is coaxial with, the firstcavity; a seal with a toroidal shape with an open top located in thebottom of the first cavity wherein the seal surrounds the pipe; anisolation member coupled to a sensor and extending down into the sealthrough the open top; and a collar that surrounds the isolation memberand is pressed down into the housing and into the second cavity.